Ronneburgite, K2MnV4O12, a new mineral from Ronneburg, Thuringia, Germany: Description and crystal structure

Autor(en)

Thomas Witzke, Shenyan Zhen, Karl Seff, Thomas Doering, Lutz Nasdala, Uwe Kolitsch

Abstrakt

Ronneburgite is a new chain vanadate mineral from Ronneburg, Thuringia, Germany. It occurs as reddish-brown crystals of equant, flattened, or short prismatic habit, up to 0.5 mm in length. The crystals have an adamantine luster and are translucent. Ronneburgite is biaxial negative with refractive indices na = 1.925(5), nß = 1.960(10), ny = 1.988(4), and 2Vx = 82°. Electron microprobe analysis (K2O = 16.93, MnO = 12.44, MgO = 0.62, V2O5 = 68.54; total = 98.53 wt%) gives the empirical formula 109.74(2)°. The measured density is 2.84 g/cm3; the calculated density for Z = 2 is 2.85 g/cm3. Single-crystal X-ray structure determination (R1 = 0.046 for 1846 reflections) shows that ronneburgite contains infinite vierer-single metavanadate chains [(VO3)n]n- of corner-sharing VO4 tetrahedra along [101]. Although the empirical formula and calculated bond valences indicate that V is 5+ and Mn is 2+, the crystal color, a "poor" structural compatibility index, and Mn-O distances between those expected for Mn2+-O and Mn3+-O indicate that some Mn3+ and V4+ ions are presents. K+ ions and octahedral Mnn+ ions bridge between the metavanadate chains by coordinating to their oxygen atoms.

Organisation(en)

Institut für Mineralogie und Kristallographie

Externe Organisation(en)

Rheinisch-Westfälische Technische Hochschule Aachen, University of Hawaii at Manoa, Johannes Gutenberg-Universität Mainz

Journal

American Mineralogist: an international journal of earth and planetary materials

Band

86

Seiten

1081-1086

Anzahl der Seiten

6

ISSN

0003-004X

Publikationsdatum

2001

Peer-reviewed

Ja

ÖFOS 2012

1051 Geologie, Mineralogie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/d22788b7-98b8-4903-93d5-ebf1275d19a6